May 31, 2025

There are two ways to determine how annoyed people are by aircraft noise:

This short guide will help you understand how the Air Force has pursued the second course of action.

Source: Schultz, Theodore, "Synthesis of Social Surveys on Noise Annoyance,"

Journal of the Acoustical Society of America, Vol. 64, 1978.

Table 1

Study Areas Used In The 1978 Schultz Paper

A 1978 study by Schultz based on the data in Table 1 forms the heart of the DEIS analysis. It was used by 1980 the Federal Interagency Committee on Urban Noise to establish the 65 dB threshold level and the other noise annoyance relationships in the land-use compatibility guidelines. Analyzing military aircraft noise in rural or wilderness environments with this study causes two critical problems:

Figure 1

Comparison Of The Schultz And USAF/FICON Curves

Schultz used the data from his study to develop the curve shown in Figure 1 that relates annoyance to noise levels. Schultz’s attempt to fit this curve to his data was flawed because he did not correct for ‘outlying’ data points that improperly depressed the lower section of the curve. The points scattered along the horizontal axis of Figure 1 deform the curve and cause it to give lower annoyance readings in the 50 to 75 DNL range. Correcting this error shows that the Schultz model underestimated the percentage of people who are highly annoyed at the 65 DNL level by 7 to 13 percent. Schultz wrote in 1991 that there was a fear that "agencies which fund such studies [as Schultz’s] might erroneously conclude that the synthesis [Schultz’s Curve] represented a definitive solution to many of the problems assessing effects of noise exposure on communities."

The Air Force compounded Schultz’s error with its 1994 model (also shown in Figure 1) by fitting the Schultz data with an S-shaped logistics curve. This improperly depresses the percentage of highly annoyed people in the 40 to 70 dB range by about 20% and the S-shaped curve requires one to believe that annoyance with noise grows less and less as noise increases above 75 dB--a concept supported by no acoustics research. The Air Force claims its model "does not differ substantially from the original [Schultz model], [and] is the current preferred form." In actuality, the USAF model only proves that a bad model (the Schultz curve) can be approximated by a worse model (the 1994 USAF model).

Table 2

Updated Transportation Noise Data in the 1991 Study

In 1991 Schultz co-authored a paper with Fidell and Barber updating his 1978 study. This paper again stated that the Schultz curve represents "a relationship between transportation noise exposure and the prevalence of annoyance in communities." Hence, this paper also concerns communities, not wilderness or open space, and it concerns transportation noise, not aircraft noise. The paper used 15 studies that were completed after Schultz’s original research. [See Table 2.]

The new studies cover (with one exception) either aircraft noise or ground transportation noise, but not both. Figure 2 compares two representative aircraft noise/annoyance data sets from the 1991 paper with the 1978 Schultz curve and Figure 3 compares two representative tram/traffic noise/annoyance data sets from the same paper with the 1978 Schultz curve. Each of the new studies in the 1991 paper yields the same results: annoyance with aircraft noise is consistently higher than the 1978 Schultz and 1994 USAF models forecast while annoyance with road, tram and railway noise is consistently below that indicated by these models. Only when data on aircraft noise are combined with road, tram and rail noise are the Schultz and USAF models approximated.

Figure 2

Comparison Of Aircraft Annoyance Data To Schultz Curve (1978)

This is the illogical premise on which the Schultz and Air Force models are based: lower annoyance levels with auto, tram and railroad noise are mixed with higher annoyance levels from aircraft noise to produce the average noise/annoyance levels represented by the Schultz and USAF curves. In fact, these curves represent neither kind of noise and, instead, fall in between the two groups.

Figure 3

Comparison Of Traffic/Tram Annoyance Data To Schultz Curve (1978)

Using data from studies 1, 4, 8, 9, 10, 12, and 14 in Table 2, this author constructed a new percent highly annoyed/DNL graph for aircraft noise alone. The rationale for building (and using) this new model is as follows:

Figure 4 shows the resulting model of aircraft noise based on data in 1991 Fidell, Barber and Schultz study. This model is simpler and more logical than either Schultz’s model or the USAF model--there is a direct relationship between increasing DNL levels and annoyance in the 50 to 75 DNL range.

Figure 4

Aircraft Noise/Annoyance Model Using Aircraft Data Only

The Aircraft Noise/Annoyance Model predicts that at the 65 DNL threshold point about 30 percent of people will be highly annoyed by aircraft noise. This is more than double the level of annoyance forecast by either the 1978 Schultz curve (13.6%) or the USAF model (12.3%). There is ample evidence that this model, and not the Schultz or USAF models, more closely estimates true aircraft annoyance levels. For example:

In June, 1980 a Federal Interagency Committee on Urban Noise used Schultz’s curve linking DNL and annoyance, along with other studies, to publish guidelines relating DNL and land use--the FAA Part 150 Land Use Compatibility Table. Urban land use compatibility was linked

Table 3

Linkages Between Annoyance DNL and Land Use Compatibility

to the annoyance with noise those who inhabited the land would experience. As Table 3 shows, the divisions between the six DNL/land use columns confirms the importance of annoyance in establishing the breaks between the columns of compatible activities.

Given these relationship between annoyance and land use, one can apply the results of the Aircraft Noise/Annoyance Model from Figure 4 to the land use compatibility table. For example, at the threshold DNL level of 65, the Aircraft Noise/Annoyance Model predicts that about 30 percent of people will be annoyed. This corresponds to land use compatibility category 3, where residential use should not be attempted and where schools, outdoor amphitheaters, nature exhibits and zoos should not be built. Given these standards, the uses of airspace in this DEIS would not be possible at a DNL of 65. Or, viewed in reverse, the land use compatibility category of less than 65 DNL corresponds to an annoyance level of about 15 percent highly annoyed. This, in turn, corresponds to a 53 DNL level when aircraft noise alone is considered. This corresponds to the noise emitted by an A-10 at 20,000 feet altitude. All other aircraft in the DEIS exceed this level at all altitudes.

Aside from a general, one page discussion, the DEIS is strangely silent on the likely impacts of aircraft noise on wilderness users and inhabitants. Appendix K of the DEIS attempts to justify the compatibility of aircraft noise and recreation activities by citing the FAA land-use compatibility guidelines. However, these guidelines are for urban environments only and they often assume individuals are protected from the ambient sound environment by buildings that lower the dB levels to the 20dB to 35dB range. Obviously, these figures were never meant to apply to someone in the wilderness. Similarly, neither the 1978 Schultz paper, the 1991 Fidell, Barber and Schultz paper, nor the 1994 USAF study applies to wilderness noise experiences. All the data for these studies were gathered in urban locations. The DEIS itself states on numerous occasions that the data it uses depict "the noise impact in airport communities..." or on communities in general.

That urban noise data do not apply to wilderness noise problems is both common sense and common knowledge. This was confirmed in a recent Forest Service study that suggests that persons in wilderness settings are at least ten times more sensitive to aircraft noise than those in urban settings. Although the Air Force did discuss the study in the DEIS, it failed to mention this finding and its interpretation of the data in the rest of the study is questionable to the point of being disingenuous. Based on the noise calculations in the DEIS, the level of increased sensitivity reported in the Forest Service study would require an addition of approximately a 30 dB penalty beyond the levels calculated by the Aircraft Noise/Annoyance Model in the previous section. The Forest Service also found that "low-altitude, high-speed aircraft, such as those operating along MTR's, were reported as the most annoying type of aircraft to hear or see [and].....annoyance associated with over flights was more strongly related to noise exposure than to the visibility of aircraft..."